1. Field of the Invention
The present invention relates to a semiconductor device, which is constructed by coating with a resin a semiconductor element which is mounted on a substrate, and a method for producing the semiconductor device.
2. Description of the Related Art
Recently, information portable apparatus, such as a camera, a camcorder, a cellular phone, and a personal digital assistant, and information equipment, such as an LBP (Laser Beam Printer), an ink jet printer, and a copier, are requested for miniaturization, weight saving, thinning, and cost reduction. Also in semiconductor devices embedded into these, the same needs as mentioned have been growing very much. As a semiconductor device for achieving the above-mentioned requests, a semiconductor device, which does not have leads, such as a COB (Chip On Board) package and a leadless package, is publicly known.
FIG. 4 is a schematic diagram illustrating a general conventional semiconductor device in which a semiconductor element is mounted on a substrate. A description will be performed according to FIG. 4.
An end face 101 has through holes 102, and not only a dry film 103 is laminated on the through holes 102 to block up the through holes 102, but also a semiconductor element 106 is fixedly mounted on a substrate 105 on which a wiring pattern 104 is formed. Next, the semiconductor device has structure as a semiconductor device 109 in which the semiconductor element, gold wires and connecting portions are entirely coated with a resin 108 after electrodes of the semiconductor element, and the wiring pattern 104 of the substrate 105 are electrically connected with gold wires 107.
As the substrate, there is a resin substrate, a metal substrate, a ceramic substrate, or the like. As the resin, generally, an epoxy resin and the like are used and a production method with high mass-productiveness, such as transfer molding and compression molding which use a molding, a dispenser method and a printing method, is used. When a semiconductor element is a photo sensor or a light emitting element, a light transmitting epoxy resin and the like are used.
In such a production method of the semiconductor device, in the case that patterns exist on both faces of a substrate and the substrate having both faces of which are made conductive with through holes is sealed with a liquid epoxy resin, a covering member (dry film or the like) on through holes may not be provided. In this case, the resin flows into the through holes and a malfunction arises in soldering in a post process. In particular, when a through hole, which provides in an end face of a semiconductor device, becomes an electrode for soldering to be performed with another circuit board, poor soldering may be generated in many cases because there is a sealing resin in the through hole. Hence, in a semiconductor device having construction of providing a through hole in an end face of a substrate and performing soldering in the end face, a device in which a sealing resin does not adhere to the through hole is necessary. As a unit to solve this problem, there is a unit which becomes public knowledge with Japanese Patent Application Laid-Open No. H08-107161 and Japanese Patent Application Laid-Open No. H10-135492.
In both electronic parts disclosed in the above-mentioned official gazettes, by covering through holes of each substrate with a covering member, such as a dry film, inflow of a liquid resin into the through hole is prevented.
In addition, in an electronic part described in Japanese Patent Application Laid-Open No. 2003-008077, by filling up a through hole interior with a liquid resist and curing the resist thereafter, a resin of a resin sealed body is prevented from permeating in the through hole.
Here, even when there is no sealing resin in a through hole of a semiconductor device, when a wiring portion of the through hole of the semiconductor device is soldered to another circuit board, soldering strength lacks without a through hole land. In addition, this causes a quality problem that a soldering inspection cannot be performed securely.
On the other hand, for resin sealing of a substrate in which a plurality of semiconductor elements is mounted lengthwise and crosswise, the transfer molding with high mass-productiveness is generally used as mentioned above to become public knowledge. Such methods are described in Japanese Patent Application Laid-Open No. H11-077734 and Japanese Patent Application Laid-Open No. 2000-299335.
A transfer molding method using a release film is described in the above-mentioned Japanese Patent Application Laid-Open No. H11-077734. In the above-mentioned Japanese Patent Application Laid-Open No. 2000-299335, a method of performing resin molding with pressing a position exposed to an external surface of a molded product with a release film is disclosed.
Furthermore, in an electronic part in Japanese Patent Application Laid-Open No. H11-074410 (refer to FIG. 12), although coating an electronic element on a substrate, a sealing resin is provided apart from through holes where upper surface electrodes are connected. In the production method, a molding covers a through hole line.
Nevertheless, since a covering member, such as a dry film, is used over through holes in the electronic parts in Japanese Patent Application Laid-Open No. H08-107161 and Japanese Patent Application Laid-Open No. H10-135492, cost increases because of an addition to a member and a process increase. In addition, in consideration of accurate adhesion and flashing of an adhesive for the dry film, it is necessary to secure a space for laminating the dry film, which is disadvantageous structure for miniaturization. Although a space of a member is not needed in the electronic part in Japanese Patent Application Laid-Open No. 2003-008077, since cost necessary for curing of a resist agent and cost necessary for etching are needed, it becomes expensive.
On the other hand, although a transfer molding method which is high in mass-productiveness is disclosed in Japanese Patent Application Laid-Open No. H11-077734, it is necessary to block up through holes, and hence, this cannot be also miniaturized and becomes expensive.
In addition, when soldering a wiring portion of through holes of the semiconductor device with another circuit board, poor soldering strength is caused, and it is not possible to inspect whether soldering is performed securely.
In Japanese Patent Application Laid-Open No. 2000-299335, although the method of performing resin molding with pressing a position exposed to an external surface of a molded product with a release film is disclosed, this does not arrived to an idea of prevention of inflow of a resin into a through hole.
Furthermore, in an electronic part in Japanese Patent Application Laid-Open No. H11-074410, through holes in a substrate are made into a face where a sealing resin does not flow. Nevertheless, it is not intended to achieve compatibility of an increase of soldering strength by suction of solder with facilitation of a visual inspection of whether soldering is performed properly.